It has already been proposed to introduce yarns into a yarn guide by means of a blowing nozzle (German Offenlegungsschrift 3,701,671).
The object on which the invention is based is to combine such a device with a yarn-changing device and so design it that it works in an operationally reliable way.
The set object is achieved, according to the invention, by means of a device of the type mentioned in the introduction, in that the yarn blowing-in nozzle of the device is formed in a nozzle head having inlet channels for a plurality of yarns and preceded by a yarn-proportioning part which for each of the plurality of yarns has a yarn-loop region located respectively between a front and a rear separately actuable yarn-clamping point and which is equipped with at least one yarn looper. Advantageously, a cutting-off device conventional on yarn-changing devices can be combined with the threading and yarn-changing device, and it can be arranged in the effective range of at least one yarn guide together with a yarn-clamping device for a yarn guided through the yarn guide and coming out of the yarn guide. The device can be arranged in a stationary manner, so that the yarn guides have to be fed to it for equipment or for the yarn change. However, the device together with its plurality of parts can also be made movable, so that it can be brought to the yarn guides.
The combined threading and yarn-changing device according to the invention allows an automatic equipment of the yarn guides and an automatic change of the yarns guided by them. On flat knitting machines, by means of the device designed according to the invention either the number of yarn guides used and to be controlled individually can be reduced, because a separate yarn guide no longer has to be provided for every colour or yarn type employed, or the device makes it possible to use a number of different yarns which exceeds the number of yarn guides to be employed on the machine.
The threading and yarn-changing device is so designed that a knitting machine does not have to be stopped in order to introduce a yarn into a yarn guide or to change the yarn. The high operating reliability required for this is achieved by means of a simple construction of the device, whereby the yarn-proportioning part can have a yarn looper common to all the yarns and in the form of a blowing-nozzle bar extending transversely relative to all the yarns and arranged above the plurality of yarn-loop regions. But a mechanically active yarn follow-up web lowerable into the plurality of yarn-loop regions arranged next to one another can also be provided as a yarn looper. By means of the blowing-nozzle bar or the yarn follow-up web, storage loops are formed in the yarn-proportioning device for each yarn to a length which is sufficient for a yarn to be introduced to be brought through the yarn guide into the additional clamping device or for it to be drawn back out of the yarn guide again into the nozzle head behind the blowing nozzle. The yarn-clamping points in front of and behind each of the yarn-loop regions of the yarn-proportioning device appropriately all arranged next to one another can advantageously each have a spring-loaded movable clamping jaw which is coupled to a pneumatic, hydraulic, electrical or mechanical adjusting member. The yarn-clamping points ensure either that a formed yarn loop remains protected as long as the respective yarn is not inserted, or that, to form the yarn loop, yarn can either be drawn off from a storage reel or be drawn back out of a yarn guide via the nozzle head, or else that an inserted yarn has a free run through the yarn-proportioning part.
An exemplary embodiment of a threading and yarn-changing device designed according to the invention is explained in more detail below by means of the accompanying drawing.